title: Titanocene(III)-catalyzed 6-exo versus 7-endo cyclizations of epoxypolyprenes: efficient control and synthesis of versatile terpenic building blocks.
abstract: In this article, a complete study on the selectivity of titanocene(III) cyclization of epoxypolyprenes is presented. The requirements for the formation of six- or seven-membered rings during these cyclizations are determined, taking into account the different substitution pattern in the epoxypolyprene precursor. Thus, a complete selectivity to 6-exo or 7-endo cyclization process has been achieved, yielding mono-, bi-, and even tricyclic compounds, constituting a new and efficient access to this type of derivative. Additionally, this procedure opens the possibility to prepare excellent building blocks for the synthesis of polycyclic compounds with a trisubstituted oxygenated function, which is present in several natural terpenes.
authors.affiliation: Department of Organic Chemistry, Faculty of Science University of Granada, C. U. Fuentenueva s/n, 18071 Granada (Spain). jjusti@ugr.es.
authors.forename: José
authors.initials: J
authors.lastname: Justicia
authors.forename: Tania
authors.initials: T
authors.lastname: Jiménez
authors.forename: Delia
authors.initials: D
authors.lastname: Miguel
authors.forename: Rafael
authors.initials: R
authors.lastname: Contreras-Montoya
authors.forename: Rachid
authors.initials: R
authors.lastname: Chahboun
authors.forename: Enrique
authors.initials: E
authors.lastname: Alvarez-Manzaneda
authors.forename: Daniel
authors.initials: D
authors.lastname: Collado-Sanz
authors.forename: Diego J
authors.initials: DJ
authors.lastname: Cárdenas
authors.forename: Juan M
authors.initials: JM
authors.lastname: Cuerva
mesh_terms: D002384:Catalysis; D003500:Cyclization; D004852:Epoxy Compounds / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D013729:Terpenes / Q000138:chemical synthesis / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D004852:Epoxy Compounds; D005609:Free Radicals; D009942:Organometallic Compounds; D013729:Terpenes; C406884:titanocene
keywords: cyclic compounds; cyclization; natural products; radicals; titanium